Spot occupied by male, adult showing endurance (7)
I believe the answer is:
stamina
'endurance' is the definition.
(I know that stamina is a type of endurance)
'spot occupied by male adult' is the wordplay.
'spot' becomes 'stain' (synonyms).
'occupied by' means one lot of letters goes inside another.
'male' becomes 'm' (common abbreviation).
'adult' becomes 'a' (abbreviation).
'stain' placed around 'm' is 'stamin'.
'stamin'+'a'='STAMINA'
'showing' is the link.
(Other definitions for stamina that I've seen before include "toughness in > male parts" , "Indefatigability" , "perseverance" , "Resilience" , "Enduring energy" .)