Attack a small man taking lead (7)
I believe the answer is:
assault
'attack' is the definition.
(I know that assault is a type of attack)
'a small man taking lead' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'man' becomes 'saul' ().
'lead' says to take the initial letters.
The first letter of 'taking' is 't'.
'a'+'s'+'saul'+'t'='ASSAULT'
(Other definitions for assault that I've seen before include "Sudden violent attack" , "Storm" , "Launch an attack on" , "raid" , "Onslaught" .)