Clear where to write solutions, except the first (3)
I believe the answer is:
rid
'clear' is the definition.
(synonyms)
'where to write solutions except the first' is the wordplay.
'where to write solutions' becomes 'grid' (where crossword solutions are written).
'except the first' means to remove the first letter.
'grid' with its initial letter removed is 'RID'.
(Other definitions for rid that I've seen before include "Free from something unpleasant" , "Free, relieve" , "Lose, shake off" , "Free (someone of something unwanted)" , "Free, disencumber" .)