Deer? Sounds like a cow at end of lane (5)
I believe the answer is:
moose
'deer?' is the definition.
(moose is a kind of deer)
'sounds like a cow at end of lane' is the wordplay.
'sounds like a cow' becomes 'moos' (cows go moo).
'at end of' suggests the final letters.
The final letter of 'lane' is 'e'.
'moos'+'e'='MOOSE'
(Other definitions for moose that I've seen before include "Ungulate" , "beasts" , "Large US deer" , "US deer with enormous antlers" , "Large northern deer" .)