Old sign about five internal organs (7)
I believe the answer is:
ovaries
'internal organs' is the definition.
'ovaries' can be an answer for 'organs' (ovary is a kind of organ). I'm not sure about the 'internal' bit.
'old sign about five' is the wordplay.
'old' becomes 'o' (abbreviation).
'sign' becomes 'aries' (star sign).
'about' is a charade indicator (letters next to each other).
'five' becomes 'V' (Roman numeral).
'aries' put after 'v' is 'varies'.
'o'+'varies'='OVARIES'
Can you help me to learn more?
(Other definitions for ovaries that I've seen before include "egg production unit" , "Egg-producing organs in female animals" .)