Stray dog's lead split (5)
I believe the answer is:
drift
'stray' is the definition.
(I know that stray can be written as drift)
'dog's lead split' is the wordplay.
'lead' suggests taking the first letters.
'split' becomes 'rift' (I've seen this in other clues).
The initial letter of 'dogs' is 'd'.
'd'+'rift'='DRIFT'
(Other definitions for drift that I've seen before include "See 8" , "Slide" , "Walk casually; snow pile" , "Move with the current" , "Trend; meaning" .)