Dog cross about garland (7)
I believe the answer is:
spaniel
'dog' is the definition.
(spaniel is a kind of dog)
'cross about garland' is the wordplay.
'cross' becomes 'span' (span can mean to cross or bridge).
'about' says the letters should be written in reverse.
'garland' becomes 'lei' (synonyms).
'lei' written backwards gives 'iel'.
'span'+'iel'='SPANIEL'
(Other definitions for spaniel that I've seen before include "Droopy-ear dog" , "Droopy-eared dog" , "Alpines (anag)" , "Type of dog" , "Dog with drooping ears" .)