Cook stepped around lobster for one (7)
I believe the answer is:
decapod
'lobster for one' is the definition.
(lobster is a kind of decapod)
'cook stepped around' is the wordplay.
'cook' becomes 'do' (I've seen this in other clues).
'stepped' becomes 'paced' (to pace is to take a step).
'around' says the letters should be written backwards.
'do'+'paced'='dopaced'
'dopaced' in reverse letter order is 'DECAPOD'.
(Other definitions for decapod that I've seen before include "Crab or lobster" , "Say, crab" , "sea creature" , "lobster, say" , "Such as shrimp or lobster" .)