Bird, favourite on lake (6)
I believe the answer is:
petrel
'bird' is the definition.
(petrel is a kind of bird)
'favourite on lake' is the wordplay.
'favourite' becomes 'pet' (synonyms).
'on' becomes 're' ('on' can be mean 'with reference to').
'lake' becomes 'l'.
'pet'+'re'+'l'='PETREL'
(Other definitions for petrel that I've seen before include "Seabird (that may be stormy)" , "Seabird sounds like fuel" , "Small seabird" , "Seabird that flies far from land" , "18's [BIRD]" .)