Ordering hardtop or crustacean, say (9)
I believe the answer is:
arthropod
'crustacean say' is the definition.
(crustacean is a kind of arthropod)
'ordering hardtop or' is the wordplay.
'ordering' is an anagram indicator.
'hardtop'+'or'='hardtopor'
'hardtopor' is an anagram of 'ARTHROPOD'.
(Other definitions for arthropod that I've seen before include "Invertebrate" , "One has external skeleton" , "worker, perhaps" , "spider, for example" , "Such as a crustacean or spider" .)