Brooder's pulse is abnormal — a possible cause for medical concern (5,8)
I believe the answer is:
blood pressure
'a possible cause for medical concern' is the definition.
'brooder's pulse is abnormal' is the wordplay.
'is abnormal' is an anagram indicator.
'brooders'+'pulse'='brooderspulse'
'brooderspulse' is an anagram of 'BLOOD PRESSURE'.
(Other definitions for blood pressure that I've seen before include "110/70 approximately for a healthy adult?" , "It is measured by sphygmometer" , "It's high over 140/90mmHg" , "See 20" , "vital sign" .)