Deduce no much-quoted poem's been written about 'er (5)
I believe the answer is:
infer
'deduce' is the definition.
(synonyms)
'no much-quoted poem's been written about 'er' is the wordplay.
I cannot really see how this works, but
'no' could be 'n' (common abbreviation) and 'n' is located in the answer.
''er' could be 'er' and 'er' is found within the answer.
'poem' could be 'if' (Rudyard Kipling poem) and 'if' is found within the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for infer that I've seen before include "Presume" , "Derive as a consequence" , "Conclude by reasoning" , "Deduce (from evidence)" , "Take or gather meaning from" .)