Check around river for homeless animal (5)
I believe the answer is:
stray
'homeless animal' is the definition.
(I've seen this in another clue)
'check around river for' is the wordplay.
'check' becomes 'stay' (synonyms).
'around' indicates putting letters inside.
'river for' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'stay' going around 'r' is 'STRAY'.
Can you help me to learn more?
(Other definitions for stray that I've seen before include "Deviate" , "Wander from the path" , "out of place" , "Depart from the right path" , "Homeless cat" .)