Repercussion when retired engineer gets to house (4)
I believe the answer is:
echo
'repercussion' is the definition.
(thesaurus)
'retired engineer gets to house' is the wordplay.
'retired' shows that the letters should be reversed in order.
'engineer' becomes 'ce'.
'gets' is a charade indicator (letters next to each other).
'to house' becomes 'ho' (abbreviation for house).
'ce' in reverse letter order is 'ec'.
'ec'+'ho'='ECHO'
'when' acts as a link.
(Other definitions for echo that I've seen before include "Send back" , "Parrot" , "In The Maid of the Mountains" , "Greek girl in love with Narcissus" , "Audio effect" .)