Stress in past, for example, ultimately can make us nervous (9)
I believe the answer is:
tenseness
'stress' is the definition.
(I know that stress can be written as tenseness)
'past for example ultimately can make us nervous' is the wordplay.
'past for example' becomes 'tense' (past tense).
'ultimately' suggests the final letters.
The last letters of 'can make us nervous' are 'ness'.
'tense'+'ness'='TENSENESS'
'in' acts as a link.
(Other definitions for tenseness that I've seen before include "Condition of being taut" , "Cosmetic lotion" .)