Tongue held by paramour, dutifully (4)
I believe the answer is:
urdu
'tongue' is the definition.
(Urdu is a language or tongue)
'held by paramour dutifully' is the wordplay.
'held by' indicates the answer is hidden within the clue.
'URDU' is hidden within 'paramour dutifully'.
(Other definitions for urdu that I've seen before include "Pakistani language" , "Language spoken by Moslems in Pakistan and India" , "Language closely related to Hindi" , "Asian language written in Arabic script" , "Language akin to Hindi" .)