Hasten with throng avoiding cold (4)
I believe the answer is:
rush
'hasten' is the definition.
(I know that hasten can be written as rush)
'throng avoiding cold' is the wordplay.
'throng' becomes 'crush' (I've seen this in another clue).
'avoiding' indicates named letters should be taken away.
'cold' becomes 'c' (eg on taps).
'crush' with 'c' taken away is 'RUSH'.
'with' acts as a link.
(Other definitions for rush that I've seen before include "Spate" , "'Hurry, haste (4)'" , "Marsh plant - fly" , "plant developing on shore" , "Traffic is busiest at this hour" .)