Ditch worker perhaps is cutting (9)
I believe the answer is:
trenchant
'is cutting' is the definition.
(I've seen this before)
'ditch worker' is the wordplay.
'ditch' becomes 'trench' (synonyms).
'worker' becomes 'ant' (worker is a type of ant).
'trench'+'ant'='TRENCHANT'
'perhaps' acts as a link.
(Other definitions for trenchant that I've seen before include "Incisive in expression" , "Forthright, vigorous" , "Showing keenness" , "Incisive in style" , "blunt" .)