專心致志

专 = 二 + ㇉ + ㇏ : Let's say the expert is a scientist. Also, 专 reminds me a little bit of the wheelchair symbol. Thus I choose a scientist in a wheelchair as symbol for 专.

专 = 二 + ㇉ + ㇏ : In front of the anthill, the scientist and Julian Giant Squid are focused on one thing: Electrifying the wheelchair of the scientist. Deeply concentrated they connect a capacitor to the wheelchair, which indeed starts to move a little.

心 = 乚 + 丶 : Marie Curie (xi) uses a shovel (乚) to dig a hole in front of the encampment ((e)n1). She wants to bury her heart (心). To the side are three petal leaves (丶), with which she wants to cover it afterwards.

致 = 攵 + 至 : James II of England (zh) sends (致) off his beloved exquisite (致) sledgehammer (攵) in the space station's bathroom (Ø4) using the station's conveyor belt (至).

志 = 士 + 心 : Mnemonic symbol: a sticky note. James II of England (zh) writes down his poems on sticky notes (志) in the space station's bathroom (Ø4). As he reads them to the bachelor (士), the bachelor is really moved by James II of England's ambitions (志) and wants to give James II of England his heart (心).