Eccentric old females on regular route (7)
I believe the answer is:
offbeat
'eccentric' is the definition.
(I've seen this before)
'old females on regular route' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'females' becomes 'ff' (I've seen this in other clues).
'on' says to put letters next to each other.
'regular route' becomes 'beat' (eg a police officer's beat).
'o'+'ff'+'beat'='OFFBEAT'
(Other definitions for offbeat that I've seen before include "Quirky" , "Unconventional or lacking rhythm" , "Wacky; syncopated" , "Odd, unconventional" , "Unusual, not ordinary - or rhythmic" .)