It's present in a constantly recurring form (10)
I believe the answer is:
persistent
'recurring form' is the definition.
'persistent' can be an answer for 'recurring' (thesaurus). I'm not sure about the 'form' bit.
'it's present in a constantly' is the wordplay.
'present' is an anagram indicator (I've seen 'presenting' mean this).
'in' means one lot of letters goes inside another.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'constantly' becomes 'sent' (I can't justify this - if you can you should give a lot more credence to this answer).
'its' with letters rearranged gives 'ist'.
'per'+'sent'='persent'
'ist' going inside 'persent' is 'PERSISTENT'.
Can you help me to learn more?
(Other definitions for persistent that I've seen before include "Resolute - interminable" , "not giving up" , "Prolonged; nagging" , "Relentless" , "Ongoing" .)