Bound to go without food with aim to restrict energy (8)
I believe the answer is:
fastened
'bound' is the definition.
(thesaurus)
'go without food with aim to restrict energy' is the wordplay.
'go without food' becomes 'fast' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'aim' becomes 'end' (I've seen this before).
'to restrict' indicates putting letters inside.
'energy' becomes 'e' (physics symbol as in E=mc2).
'end' enclosing 'e' is 'ened'.
'fast'+'ened'='FASTENED'
'to' is the link.
(Other definitions for fastened that I've seen before include "Secured - buckled" , "Stapled" , "Buttoned, secured" , "Buttoned, tied" .)