I taxi over after heading to Ann Summers (5)
I believe the answer is:
abaci
'summers' is the definition.
(I've seen this before)
'i taxi over after heading to ann' is the wordplay.
'taxi' becomes 'cab' (synonyms).
'over' shows that the letters should be reversed in order.
'after' is a charade indicator (letters next to each other).
'heading to' says to take the initial letters (the head of the word).
The initial letter of 'ann' is 'a'.
'i'+'cab'='icab'
'icab' reversed gives 'baci'.
'baci' after 'a' is 'ABACI'.
(Other definitions for abaci that I've seen before include "Counting devices" , "Early computers" , "You can count on them" , "Counting-frames" , "They can be counted on" .)