Scrupulous doctor able to absorb material without pressure (8)
I believe the answer is:
rigorous
'scrupulous' is the definition.
(thesaurus)
'doctor able to absorb material without pressure' is the wordplay.
I cannot really see how this works, but
'doctor' could be 'rig' (both can mean to manipulate or tamper with) and 'rig' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rigorous that I've seen before include "'Strict, harsh, severe (8)'" , "firm" , "Austere" , "Strict as discipline may be" , "Painstakingly careful and accurate" .)