Answer magazine's boss gives prematurely (5,2,4)

'prematurely' is the definition.
Both the answer and definition are adverbs. Perhaps there's an association between them I don't understand?

'answer magazine's boss' is the wordplay.
I cannot really see how this works, but
'answer' could be 'a' (abbreviation eg in Q and A) and 'a' is present in the answer.
'boss' could be 'head' (synonyms) and 'head' is found in the answer.
'magazine' could be 'time' (US magazine) and 'time' is found in the answer.
The remaining letters 'of' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

'gives' acts as a link.

Can you help me to learn more?