Most skilful answer? Lucky (6)
I believe the answer is:
ablest
'most skilful' is the definition.
(most able)
'answer? lucky' is the wordplay.
'answer?' becomes 'a' (abbreviation eg in Q and A).
'lucky' becomes 'blest' (archaic spelling of 'blessed').
'a'+'blest'='ABLEST'
(Other definitions for ablest that I've seen before include "Like pupils in top stream" , "Most suitable" , "Most proficient" , "Most capable" , "Are highly favoured like" .)