The most common and most likely answer to this crossword clue is the 6 letter word ATHROB
A
T
H
R
O
B
More clues leading to the result ATHROB
- What fills towelling gown is pounding
- After shower every morning one’s in bed, ripping?
- Beating cheers up hard little boy
- A mostly shy beginner in band is drumming
- Having an active erection, so towelling garment needs ends removing
- In a state of excitement as edges of dressing gown fall away
- At start of battle, supporting mounted men with hearts pulsating
- Thrilling, a non-western cast coming to Britain
- Shuddering, as après-swimwear is uncovered
- Attending hotel, cheat gets beating
Buddy explains!

The straight part
We know that "having an active erection" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case having an active erection = athrob.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.