He figures to be useful for steering (4)
I believe the answer is:
helm
'useful for steering' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'he figures' is the wordplay.
'figures' becomes 'lm' (I can't explain this - if you can you should believe this answer much more).
'he'+'lm'='HELM'
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for helm that I've seen before include "Steersman's place" , "protection for nut once" , "Steering device" , "Part of ship" , "Steering mechanism" .)