What I can do for ’Arry! (3)
I believe the answer is:
ear
'what i can do for 'arry' is the definition.
The definition suggests a singular noun which matches the answer.
'what i' is the wordplay.
I cannot quite understand how this works, but
'i' could be 'a' and 'a' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for ear that I've seen before include "good sense of music" , "Seed container" , "Spike of, eg, corn" , "organ with drum" , "Place for a plug" .)