The most common and most likely answer to this crossword clue is the 7 letter word ROCKING
I've seen this crossword clue in The Times
R
O
C
K
I
N
G
Buddy explains!
The straight part
We know that "Mounting attraction in the nursery" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mounting attraction in the nursery = rocking.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.
What does ROCKING mean?
ROCKING verb- To move gently back and forth.
- To cause to shake or sway violently.
- To sway or tilt violently back and forth.
- (of ore etc.) To be washed and panned in a cradle or in a rocker.
- To disturb the emotional equilibrium of; to distress; to greatly impact (most often positively).
- To do well or to be operating at high efficiency.
- To make love to or have sex with.
- To play, perform, or enjoy rock music, especially with a lot of skill or energy.
- To be very favourable or skilful; excel; be fantastic.
- To thrill or excite, especially with rock music
- To do something with excitement yet skillfully
- To wear (a piece of clothing, outfit etc.) successfully or with style; to carry off (a particular look, style).
- The motion of something that rocks.
- The abrading of a copper plate with a rocker, preparatory to mezzotinting.
- The motion by which the design on a steel mill is transferred to a copper cylinder.
- Shaking, swaying or moving back and forth.
- Excellent; great.