Poet curtailed attempt to install program (6)
I believe the answer is:
sappho
'poet' is the definition.
(ancient Greek poet)
'curtailed attempt to install program' is the wordplay.
'curtailed' means to remove the last letter.
'attempt' becomes 'shot' (shot is a kind of attempt).
'to install' means one lot of letters goes inside another (inserted letters are installed).
'program' becomes 'app' (type of computer program).
'shot' with its last letter taken off is 'sho'.
'sho' enclosing 'app' is 'SAPPHO'.
(Other definitions for sappho that I've seen before include "Sixth century BC Greek poetess" , "Pa hops around the ancient Greek poetess" , "Greek lyric poet of Lesbos" , "Greek female poet" , "Greek lyric poetess" .)