Permit everything round the start of winter (5)
I believe the answer is:
allow
'permit' is the definition.
(synonyms)
'everything round the start of winter' is the wordplay.
'everything' becomes 'all' (I've seen this before).
'round' becomes 'o' (round can mean a round object).
'the start of' says to take the initial letters.
The initial letter of 'winter' is 'w'.
'all'+'o'+'w'='ALLOW'
(Other definitions for allow that I've seen before include "Permit or agree" , "Give leave to" , "Permit, consent to" , "Permit, let happen" , "Acknowledge - concede" .)