Rents complex from Government with most of the power (8)
I believe the answer is:
strength
'power' is the definition.
(strength is a kind of power)
'rents complex from government with most of the' is the wordplay.
'complex' is an anagram indicator.
'from' says to put letters next to each other.
'government' becomes 'g'.
'with' says to put letters next to each other.
'most of' means to remove the last letter.
'the' with its final letter removed is 'th'.
'rents' anagrammed gives 'stren'.
'stren'+'g'+'th'='STRENGTH'
(Other definitions for strength that I've seen before include "Toughness, force" , "Force, firmness" , "Beneficial attribute" , "Fortitude" , "Physical potency" .)