Expertise for you and I takes two seconds (7)
I believe the answer is:
prowess
'expertise' is the definition.
(I've seen this before)
'for you and i takes two seconds' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'you and i' becomes 'we'.
'takes' says to put letters next to each other.
'two seconds' becomes 'ss' (abbreviation for second times two).
'pro'+'we'+'ss'='PROWESS'
(Other definitions for prowess that I've seen before include "Ability, expertise" , "Acquired skill(s)" , "courage" , "Outstanding skill" , "'Skill, expertise (7)'" .)