All but fifteen caught out (2,6)
I believe the answer is:
in effect
'all' is the definition.
Both the definition and answer are adjectives. Maybe there's an association between them I don't understand?
'fifteen caught out' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'fifteen'+'c'='fifteenc'
'fifteenc' anagrammed gives 'IN EFFECT'.
'but' acts as a link.
Can you help me to learn more?
(Other definitions for in effect that I've seen before include "to all intents and purposes" , "Really, as a matter of fact" , "Really, or in essence" , "Really; operative" , "Really; operating" .)