Pub Heather left after sister's initial round (9)
I believe the answer is:
spherical
'round' is the definition.
(similar in meaning)
'pub heather left after sister's initial' is the wordplay.
'pub' becomes 'ph' (abbreviation).
'heather' becomes 'erica' (the plant genus Erica includes heather plants).
'left' becomes 'l' (common abbreviation).
'after' means one lot of letters go next to another.
'initial' says to take the initial letters.
The first letter of 'sisters' is 's'.
'ph'+'erica'+'l'='pherical'
'pherical' after 's' is 'SPHERICAL'.
(Other definitions for spherical that I've seen before include "As balls" , "Ball-shaped" , "Like cannonballs" , "Globe-shaped" , "Rotund" .)