Substantial latitude given about source of computer memory (6)
I believe the answer is:
recall
'memory' is the definition.
(I know that recall is a type of memory)
'substantial latitude given about source of computer' is the wordplay.
'substantial' becomes 'real' (synonyms).
'latitude' becomes 'L' (abbreviation for latitude).
'given about' indicates putting letters inside.
'source of' says to take the initial letters (the start - or source - of the word).
The initial letter of 'computer' is 'c'.
'real'+'l'='reall'
'reall' enclosing 'c' is 'RECALL'.
(Other definitions for recall that I've seen before include "cancel" , "Summon back or bring to mind" , "Summon back, perhaps to mind" , "Hark back" , "Evoke" .)