Criticises half-hearted search for taxi to return (7)
I believe the answer is:
rebukes
'criticises' is the definition.
(rebuking is a kind of criticising)
'half-hearted search for taxi to return' is the wordplay.
'half hearted search' becomes 'kes' (I can't justify this - if you can you should believe this answer much more).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'taxi' becomes 'uber'.
'to return' is a reversal indicator.
'uber' back-to-front is 'rebu'.
'kes' after 'rebu' is 'REBUKES'.
(Other definitions for rebukes that I've seen before include "Strong reprimands" , "Admonishes sharply or severely" , "Admonishes, chides" , "Expresses sharp disapproval" .)