On having departed this evening, stretched (5)
I believe the answer is:
tight
'stretched' is the definition.
(I've seen this before)
'on having departed this evening' is the wordplay.
'having departed' indicates named letters should be taken away.
'this evening' becomes 'to-night' (synonyms).
'tonight' with 'on' removed is 'TIGHT'.
(Other definitions for tight that I've seen before include "Miserly (informal) - drunk (informal)" , "Drunk - under control" , "Miserly or blotto" , "Drunk; restricted" , "Close-fitting; tense" .)