Foolish blasphemy rejected by base, makes reference to body fluid (5)
I believe the answer is:
lymph
'body fluid' is the definition.
(lymph is a kind of body fluid)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for lymph that I've seen before include "Fluid associated with a gland" , "Bodily fluid" , "White blood cell fluid" , "Watery fluid containing white blood cells" , "Body fluid" .)