Skilful with it, a rod at sea (6)
I believe the answer is:
adroit
'skilful' is the definition.
(thesaurus)
'it a rod at sea' is the wordplay.
'at sea' indicates an anagram.
'it'+'a'+'rod'='itarod'
'itarod' is an anagram of 'ADROIT'.
'with' acts as a link.
(Other definitions for adroit that I've seen before include "Dextrous" , "Skilled" , "Skilful, dexterous" , "Deft and skilful" , "Deft and proficient" .)