Wintry weather at present, after first sign of spring (4)
I believe the answer is:
snow
'wintry weather' is the definition.
(I've seen this before)
'present after first sign of spring' is the wordplay.
'present' becomes 'now' (I've seen this before).
'after' means one lot of letters go next to another.
'first sign of' indicates taking the first letters (I've seen 'first signs' mean this).
The initial letter of 'spring' is 's'.
'now' put after 's' is 'SNOW'.
'at' is the link.
(Other definitions for snow that I've seen before include "Ice crystal precipitation" , "'See amid the winter's ... (Christmas carol)" , "Weather condition" , "Winter weather" , "Wintry weather" .)