Follows bad boys conserving energy (5)
I believe the answer is:
obeys
'follows' is the definition.
(I've seen this before)
'bad boys conserving energy' is the wordplay.
'bad' is an anagram indicator.
'conserving' is an insertion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'boys' anagrammed gives 'obys'.
'obys' going around 'e' is 'OBEYS'.
(Other definitions for obeys that I've seen before include "Does as one's told" , "Heeds" , "Does what one is told" , "Listens to" , "Complies with orders" .)