Touch up, freshen and sweep (8)
I believe the answer is:
airbrush
'touch up' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how one could define the other.
'freshen and sweep' is the wordplay.
'freshen' becomes 'air' (airing is a kind of freshening).
'and' is a charade indicator (letters next to each other).
'sweep' becomes 'brush' (synonyms).
'air'+'brush'='AIRBRUSH'
Can you help me to learn more?
(Other definitions for airbrush that I've seen before include "it's to smooth out the wrinkles" , "It's used to enhance a photograph" , "Represent as better than in fact - rub hairs (anag)" , "Prettify - alter a photo" , "Conceal details" .)