Man with cue, getting break, displays keen perception (6)
I believe the answer is:
'keen perception' is the definition.
(I've seen this before)
'man with cue getting break' is the wordplay.
I cannot really see how this works, but
'man' could be 'n' (knight, a man in chess) and 'n' is found in the answer.
'with' could be 'cum' ('with' in Latin) and 'cum' is found within the answer.
The remaining letters 'ae' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'displays' acts as a link.
Can you help me to learn more?
(Other definitions for acumen that I've seen before include "Mental sharpness as in business" , "Forming judgement" , "Shrewdness, intelligence in business" , "Good judgment" , "'Shrewdness, in business perhaps (6)'" .)