I will struggle with degree under pressure and strain (8)
I believe the answer is:
pedigree
'strain' is the definition.
(I know that pedigree is a type of strain)
'i will struggle with degree under pressure' is the wordplay.
'will struggle with' indicates an anagram (letters struggle or jostle around).
'under' says to put letters next to each other.
'pressure' becomes 'p' (abbreviation).
'i' mixed up with 'degree' makes 'edigree'.
'edigree' put after 'p' is 'PEDIGREE'.
'and' is the link.
(Other definitions for pedigree that I've seen before include "Genealogical table" , "Of animals, recorded line of descent" , "Record of descent" , "(Pure) ancestry" , "Blood line" .)