West perhaps welcoming reversal of brief glitch in automated communications device (4,5)
I believe the answer is:
mail merge
'automated communications device' is the definition.
'west perhaps welcoming reversal of brief glitch' is the wordplay.
'west perhaps' becomes 'mae' (Mae West).
'welcoming' is an insertion indicator (in sense of 'inviting in').
'reversal' says the letters should be written in reverse.
'of brief' means to remove the last letter (I've seen 'brief' mean this).
'glitch' becomes 'gremlin'.
'gremlin' with its final letter removed is 'gremli'.
'gremli' in reverse letter order is 'ilmerg'.
'mae' enclosing 'ilmerg' is 'MAIL MERGE'.
'in' acts as a link.
(Other definitions for mail merge that I've seen before include "printing software" , "computer program" .)