Talk is no good in oil production! (5)
I believe the answer is:
lingo
'talk' is the definition.
(thesaurus)
'no good in oil production' is the wordplay.
'no good' becomes 'ng' (abbreviation for no and good).
'in' means one lot of letters goes inside another.
'production' indicates anagramming the letters.
'oil' with letters rearranged gives 'lio'.
'ng' put inside 'lio' is 'LINGO'.
'is' acts as a link.
(Other definitions for lingo that I've seen before include "Language (slang)" , "Log in (anag.)" , "means to communicate" , "Specialised vocabulary" , "Language (informally)" .)