No, sir. The pinhead is back in jail! (6)
I believe the answer is:
prison
'jail' is the definition.
(thesaurus)
'no sir the pinhead is back' is the wordplay.
'the pinhead' becomes 'p' (head letter of 'pin').
'is back' is a reversal indicator.
'no'+'sir'+'p'='nosirp'
'nosirp' reversed gives 'PRISON'.
'in' is the link.
(Other definitions for prison that I've seen before include "Place of detention for criminals" , "Nick" , "No rips (anag)" , "punishment" , "Eg, Wormwood Scrubs" .)