Silly me loves writing puzzles after vacation! (4)
I believe the answer is:
oops
'silly me' is the definition.
(both might be said after making a mistake)
'loves writing puzzles after vacation' is the wordplay.
'loves writing' becomes 'oo' (I can't justify this - if you can you should believe this answer much more).
'after vacation' suggests removing the centre (the inside letters must vacate).
'puzzles' with its middle taken out is 'ps'.
'oo'+'ps'='OOPS'
(Other definitions for oops that I've seen before include "Harem" , "I've slipped" , "The sound of stupidity" , "statement after accident" , "Exclamation on making obvious mistake" .)