Leading Knight Templar's top icons exceptionally available for sale (2,5)
I believe the answer is:
in stock
'available for sale' is the definition.
(I've seen this in another clue)
'leading knight templar's top icons exceptionally' is the wordplay.
'leading' is a charade indicator (letters next to each other).
'knight' becomes 'k'.
'top' suggests taking the first letters.
'exceptionally' is an anagram indicator.
The first letter of 'templars' is 't'.
't'+'icons'='ticons'
'ticons' is an anagram of 'instoc'.
'k' put after 'instoc' is 'IN STOCK'.
(Other definitions for in stock that I've seen before include "Held by a shop" , "Where one may have cooked any meat" , "On the shelf" , "available" .)