Wordplay is hard to beat? (6)
I believe the answer is:
punish
'beat?' is the definition.
(I've seen this before)
'wordplay is hard' is the wordplay.
'wordplay' becomes 'pun' (synonyms).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'pun'+'is'+'h'='PUNISH'
'to' is the link.
(Other definitions for punish that I've seen before include "Sentence" , "Like wordplay in speech" , "exact retribution" , "Possibly fine" , "Castigate" .)