Itinerant actor Matt turned up, almost freezing (7)
I believe the answer is:
nomadic
'itinerant' is the definition.
(I've seen this before)
'actor matt turned up almost freezing' is the wordplay.
'actor matt' becomes 'damon' (I can't explain this - if you can you should give a lot more credence to this answer).
'turned up' shows that the letters should be reversed in order.
'almost' means to remove the last letter (most of the word but not all of it).
'freezing' becomes 'icy' (synonyms).
'damon' back-to-front is 'nomad'.
'icy' with its last letter removed is 'ic'.
'nomad'+'ic'='NOMADIC'
Can you help me to learn more?
(Other definitions for nomadic that I've seen before include "always moving?" , "Lacking fixed home" , "Itinerant" , "Migratory" , "Unsettled" .)