Dwelling briefly on final answer (6)
I believe the answer is:
result
'answer' is the definition.
(synonyms)
'dwelling briefly on final' is the wordplay.
'dwelling briefly' becomes 'res' (short for residence; 'briefly' suggests a short form).
'on' says to put letters next to each other.
'final' becomes 'ult'.
'res'+'ult'='RESULT'
(Other definitions for result that I've seen before include "Ulster (anag) - outcome" , "Verdict" , "Effect - outcome" , "'Outcome, upshot (6)'" , "'Outcome, consequence (6)'" .)