Strength and pressure wore away (5)
I believe the answer is:
power
'strength' is the definition.
(power is a kind of strength)
'pressure wore away' is the wordplay.
'pressure' becomes 'p' (abbreviation).
'away' indicates anagramming the letters.
'wore' anagrammed gives 'ower'.
'p'+'ower'='POWER'
'and' acts as a link.
(Other definitions for power that I've seen before include "Strength or authority" , "Physical force, ability" , "Possession of controlling influence" , "Military potential" , "product" .)