Bank invests pound for working man (5)
I believe the answer is:
tiler
'working man' is the definition.
(I've seen this before)
'bank invests pound' is the wordplay.
I cannot quite see how this works, but
'pound' could be 'l' (abbreviation e.g. Lsd - pounds, shillings, pence) and 'l' is present in the answer.
'bank' could be 'tier' (both can mean a row of similar things) and 'tier' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for tiler that I've seen before include "doorkeeper at lodge" , "Workman who fixes glazed rectangles in bathrooms" , "Craftsman" , "Masons' doorkeeper" , "Working man" .)