Defend very short show (9)
I believe the answer is:
vindicate
'defend' is the definition.
(thesaurus)
'very short show' is the wordplay.
'short' says to take the initial letters.
'show' becomes 'indicate' ('indicate' can be a synonym of 'show'**).
The first letter of 'very' is 'v'.
'v'+'indicate'='VINDICATE'
(Other definitions for vindicate that I've seen before include "Justify by evidence or results" , "Show to be right or justified" , "Divine cat (anag.)" , "Justify, clear" , "Justify or exonerate" .)