Little woman's surprisingly stoical — that blood pressure's at the lower end (9)

I believe the answer is:

diastolic

'that blood pressure's at the lower end' is the definition.
(diastolic refers to a phase of low blood pressure)

'little woman's surprisingly stoical' is the wordplay.
'little woman' becomes 'di' (short for Diane, Diana etc).
'surprisingly' is an anagram indicator.
'stoical' with letters rearranged gives 'astolic'.
'di'+'astolic'='DIASTOLIC'

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app