Pun unfortunately droops wanly (4,2,5)
I believe the answer is:
play on words
'pun' is the definition.
(synonyms)
'unfortunately droops wanly' is the wordplay.
'unfortunately' indicates an anagram.
'droops'+'wanly'='droopswanly'
'droopswanly' anagrammed gives 'PLAY ON WORDS'.
(Other definitions for play on words that I've seen before include "bit of a joke?" , "Pun" , "that can be ambiguous" , "form of wit" , "that may be intended humorously" .)