Dog’s nimble and he’s flexible (8)
I believe the answer is:
blenheim
'dog's' is the definition.
(I've seen this before)
'nimble and he's flexible' is the wordplay.
'and' says to put letters next to each other.
'flexible' is an anagram indicator (the word is bent into a new form).
'nimble'+'he'='nimblehe'
'nimblehe' is an anagram of 'BLENHEIM'.
(Other definitions for blenheim that I've seen before include "1704 battle; - - palace" , "Palace built for the 1st Duke of Marlborough" , "Stately home at Woodstock" , "dog" , "Oxfordshire palace; type of spaniel" .)