Mark with spots led astray installing smartphone program (6)
I believe the answer is:
dapple
'mark with spots' is the definition.
(I've seen this before)
'led astray installing smartphone program' is the wordplay.
'astray' is an anagram indicator.
'installing' indicates putting letters inside (I've seen this in other clues).
'smartphone program' becomes 'app' (I've seen this in another clue).
'led' with letters rearranged gives 'dle'.
'dle' going around 'app' is 'DAPPLE'.
(Other definitions for dapple that I've seen before include "Patch of colour or light" , "spot" , "Mottle" , "Patch of colour/light" , "Mark with spots or patches" .)