Nymph gives medic upsetting time (5)
I believe the answer is:
dryad
'nymph' is the definition.
(dryad is a kind of nymph)
'medic upsetting time' is the wordplay.
'medic' becomes 'dr'.
'upsetting' shows that the letters should be reversed in order.
'time' becomes 'day' (day is a kind of time**).
'day' back-to-front is 'yad'.
'dr'+'yad'='DRYAD'
'gives' acts as a link.
(Other definitions for dryad that I've seen before include "butterfly" , "Spirit in the wood" , "minor divinity" , "Nymph of trees" , "Woodland deity" .)