Having, during the last half-hour, cheered myself up quite a lot by filling in quite a few clues, I know that the first letter is P. Therefore it must be PEST, taking the letters from 'aPE Tried', but it still doesn't make any sense.
Only a few empty squares left now.

/ETA bit later: those empty squares are in
7 down: Fast food shop feeding trendy belle on a regular basis (9)
Letters: - N - E - E - - E
15 across: Friend friendly starting late (4
Letters A - D Y
I've been going through the alphabet but canot spot a suitable selection that makes sense. Any hint will be much appreciated.
And it'll probably be something of a kick-self, since the 7 down clue has appeared before!