Smart support worker after start of engagement (7)
I believe the answer is:
elegant
'smart' is the definition.
('elegant' can be similar in meaning to 'smart')
'support worker after start of engagement' is the wordplay.
'support' becomes 'leg' (leg is a kind of support**).
'worker' becomes 'ant' (worker is a type of ant).
'after' is a charade indicator (letters next to each other).
'start of' says to take the initial letters.
The initial letter of 'engagement' is 'e'.
'leg'+'ant'='legant'
'legant' after 'e' is 'ELEGANT'.
(Other definitions for elegant that I've seen before include "Handsome" , "Dignified and graceful" , "Refined gracefulness" , "excellent!" , "Well-turned" .)