Tease tense relative (5)
I believe the answer is:
taunt
'tease' is the definition.
(synonyms)
'tense relative' is the wordplay.
'tense' becomes 't' (grammatical abbreviation).
'relative' becomes 'aunt' (aunt is a type of relative).
't'+'aunt'='TAUNT'
(Other definitions for taunt that I've seen before include "Insult" , "Jeering remark" , "Mock provokingly" , "element of teasing" , "Goad, provoke" .)