Dog is cross; oddly ideal (7)
I believe the answer is:
spaniel
'dog' is the definition.
(spaniel is a kind of dog)
'cross oddly ideal' is the wordplay.
'cross' becomes 'span' ('span' can be a synonym of 'cross'**).
'oddly' means one should take alternating letters.
The alternate letters of 'ideal' are 'iel'.
'span'+'iel'='SPANIEL'
'is' is the link.
(Other definitions for spaniel that I've seen before include "Type of dog" , "Droopy-ear dog" , "Dog with long silky coat" , "See 1 Across" , "Springer- - -" .)